Radio broadcast distributing system



Marchfl9, 1929. I E; E. CLEMENT 1,706,377

RADIO BROADCAST DISTRIFBUTING SYSTEM 'Filed bee. 6, 1924 YS-SheetS-Sheei: 1

March 19, 1929. E. E. CLEMENT RADIO BROADCAST DISTRIBUTING SYSTEM Filed Dec. 6, 1924' 5 Sheets-Sheet 2 March 19, 1929.

E. E. CLEMENT RADIO BROADCAST DISTRfBUTING SYSTEM 5 Sheets-Sheet Filed Dec. 6, 1924 Mafch 19, 1929. E, E, CLEMENT 1,706,377

RADIO BROADCAS'I' DISTRIBUTING SYSTEM Filed Dec. 6, 1924 5 Sheets-Shet 4 3 2 LIB 1 60 lb gmwn fo'v March 19, 1929.] C E v 1306,37?

' RADIO BROADCAST DISTRIBUTiNG SYSTEM Filed- Dec. 6, 1924 -5 sheets-sheet Patented Mar, 19, 1929 UNITED STATES-[PATENT OFFICE.

EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO ED- WARD F. COLLADAY, OF WASHINGTON, DISTRICT, OF COLUMBIA.

RADIO BROADCAST DISTRIBUTING SYSTEM.

Application filed December 6, 1924. Serial No, 754,406.

My invention relates to systems of radiobroadcast distribution, and has for its object to organize such a'system so that programs may be originated, relayed, and distributed over a wide area, in a systematic and orderly manner; so that ultimate receiving stations ma be controlled and operated as subscribers stations and the programs distributed may be confined -to said subscribers stations and not "be available for. outside receiving stations not forming a part of the system; so that'sub scribers may select different programs or different items from dif-' ferent programs as time of rendition proceeds; so that subscribers ma obtain any item produced and distributed rom any part of the system to any other part of the system and within the range of their selective apparatus; so that while the subscribers may, get the full benefit of amplification and the use of vacuum tubes in'receiving and\ amplifying, yet their stations will be tubeless, that is to say, all the tubes pertaining to subscribers receiving apparatus shall be lo cated at central points, which may be also the final distributing pointsthrough which the programs or signals are given to the subscribers; so that all reception by the subscriber of programsor rogram' items selected by him, shall be di erentially metered according to the value fixed upon them by the broadcasting authorities, and automatically recorded at the rates so determined; so that asubscriber may have nothing at his station but standard telephone apparatus, connected andoperating in conjunction with telephone line eircuits,'but capable of operating a loud speaker when desired; and finally sothat the entire control, supervision, metering, current supply, installation and maintenance of subscribers instruments will be from organized central stations provided with expert operators.

I attain these and other objects which will sufficiently appear hereinafter by connecting all the subscribers stations in groups to localized central offices or exchanges, providing such exchanges with receivin instruments which may be of any suitable type, such as those described in my prior copending application, Serial No. 746,357, filed October 28, 1924, patented July 5, 1927, No.

I 1,635 )IOVldlIl line Cll'CllltS enterin a central station with yacuum tubes, one each line, constituting terminals of the lines for radio distribution; and finally connecting these distributing tubes, which may -be audio frequency amplifiers, to the output terminals of the appropriate receiving devices, and employing these connections as well as the conditions brought about by the subscribers, to operate meters, and to enable the central ofiice operators to variously control, supervise, etc.

In my prior application aforesaid, distribution tothe subscribers is by means of pure radio Waves radiated from C or local distributing stations, which in turn receive radio or wire communications from socalled B or district stations, and so on to a master station designated as A. In the system described in said application, provision is made for alternative dlstribution throughout the system by wire or by radio, and for using long waves or intermediate frequencies for carrying the audio modulations,

these intermediate frequencies or long waves beingthen transmitted either by wlre carriers or as modulations on high frequency or short radio carrier waves. In other words, the original modulations, unchanged, are passed along and-relayed from point of origin, on their long carrier waves, to the ultimate points of reception, "being multi-- plied and amplified on the way so that all transmission losses are neutralized or compensated, and" the subscribers with very simple and'inexpensiv'e instruments can receive from all points, near or far, as efiiciently as though they had the best and most powerful receivin instruments available. It is the purpose 0 the present invention to carry this a step farther, by making it possible for absolute uniformity to be obtained in the efliciency of distribution and ultimate receiving, as well as the greatest economy in apparatus, costs of installation and maintenance, and cost of service. I do this by distributing over .the subscribers wire lines, at audio frequencies, and determining the volume of current and the efiiciency of'transmission over each line individually, by using a line valve or tube at the central station. For selective purposes, the subscriber is r0 vided with a dial or other means of pro ucing impulses or the equivalent in his line, and at the central station a simple switch is associated with each line, to connect the input side of the line tube with any desired program bus or receiving instrument at the central office. These connections may be varied by the subscriber controlling his switch, from moment to moment and from item to item on the program, as desired. Where there are a number of programs receiving simultaneously, the common batteries at the central office inay be divided into groups, one for each program, so that only those subscribers lines will be tied together, even through their tubes, which are'taking the same program. Crosstalk or leakage from line to line is thus avoided.

This invention is applicable to manual, automatic or so-called semi-automatic or automanual telephone systems, as will sufiiciently appear hereinafter. The main underlying principle involved is that of relaying at the local central stations from one or more receiving instruments to a plurality of subscribers lines by means of individual line tubesor valves, so that each line may have its own selfcontained receiving unit, needing only excitation by the central ofiice rela transmitter.

T e method I have found most satisfactory in practice is to include one stage of audio amplification in each central office relay set or transmitter, the line tubes constituting asecond stage. Current carrying capacity and power of the line tubes may be varied within wide limits, affording any amount of energy for transmission and any class of service that is desired. If the exciting circuits connected to any one bus at one time are too many, the busses may be banked by means of tubes in,parallel as well understood in the art. In this case, each central ofiice receiver supplying a bus would preferably have a detector tube connected through a transformer to a plurality of audio amplifier tubes in parallel, constituting amultipled first stage, the plate circuits of which would be connected to the bus I through a suitable transformer.

Regulation of the current flow from the B or plate battery through each bus during program transmission may be obtained by means known in the art and usually manip- 1ulated by an operator at a transmitting sta- 1on. -s

Some modifications ran be made in the arrangement and many modifications in thedetail of circuit and design, but I feel the prlnciple as stated to be novel in its appli cation and original with myself, and I shall claim the same accordingly.

My invention is illustrated in panying drawings, in which:

Figs. 1 and 2 indicate, the telephone exchange portion, and broadcast distributing portion, respectively, of my combined telephone exchange and broadcast the accomdistributing system.

Fig. 3 is a modification of the circuit arrangement of Fig. 2.

diagrammatically,

ment for extending a subscribers line circuit outside the local central station. 7

Fig. 7 is a schematic diagram showing the general arrangement for distribution of a broadcast program through an amplifier circuit common to a plurality of lines and second stage amplifier tubes and circuits in- I dividual to the subscribers line.

Referring to the drawings'in detail, and first to Fig. 1 this shows the essential circuits of an ordinary telephone exchange systerm in which A is a subscribers station.

connected by line wires 6970, tothe central station C where they terminate on multiple jacks J. Similarly the multiple jacks J at the left of the figure represent the terminals of another substation line. These jacks are arranged to be interconnected through the usual answering and calling plugs PP forming the terminals of the'usual common battery cord circuit shown. Th central office terminals of each line are provided with the'usual line relay L, line lamp L and cut-ofi' relay L Where service is to be metered a recording meter'M is also individually associated with the line. Thus, the circuit arrangement here shown is that of the standard multiple switchboard, common battery, telephone exchange system, and. as such is well understood in the art further detailed description thereof will be here deferred and brought out later in the description of operation. In addition to the usual line terminal multiples 1, 2 and 3, representing multiples of the tip, ring and test \or cut-ofi' circuits, respectively, I providea fourth conductor 4 leading from a contact on the line relay along with the multiple conductors 1,2 and 3 to the'broadcast distributingsystem diagrammed in Fig. 2'.

Fig. 2 shows the broadcast distributing system of which the portion to the left of the dotted line is situated at the 'central office and connected with the subscribers telephone line terminal apparatus of the telephone central C (Fig. 1) through conductors, 1, 2, 3 and 4, while the. portion to the right of the dotted line in Fig. 2 is situated at the subscribers substation and connected with the subscribers telephone sub station apparatus A (Fig. 1) through the multiple conductors 5 and6. In Fig. 2 the subscribers line multiples l-2 terminatein contacts 7-8 of an automatic selector switch S. This position by a spring or other suitable means not shown and arranged to he stepped around by a stepping magnet 11 through a stepping pawl 12 and a ratchet 13. Also, as is usual with such switches, it is provided i with a dog 14, arranged to be thrown out of engagement with the ratchet 13 and to throw the stepping pawl 12 out of engagement when the dog is tripped by the actuation of the release magnet 15,'the energizationof the release magnet-15 effecting the tripping of the dog 14 through an extension 16 on its armature 17 pivoted at 18. To hold up the armature extension 16 until the switch has released, a trip detent 19 is provided which is pivoted at 20'and arranged to be held normally out of engagement with the hook 21 on the armature 17 by a. cam 22 on the switch shaft which permits the detent 19 to move into operative relation with the hook 2'1 whenever the switch is in off-normal position. Mounted on the switch shaft 10 are other pairs of wipers'232,4, 25-26, and 27-28. The switch S is provided with a contact bank ,containing rows of contacts 30, 31, 32 and 33 arranged to be engaged by p the switch wipers 7--8, 23s24, etc., successively'in the direction indicated by the ad Jacent arrow, it being understood that while doctors 40 and 41, the conductor 41 connecting with the coil 39 through a line supply relay 42, shunting resistance 43 and conductor 44. The. adjacent terminals of the coils, 38 and 39 are connected to the plus and minus side of the exchange common battery B through eonductors45 and 46, and bus conductors 47 and 49, respectively. In the horizontal row of contacts 31, the sixth, seventh and eighth pairs are connected individually to the batteries B, B and B respectively. In the horizontal row of c ontacts 32, the sixth, seventh and eighth pairs are connected, respectively, to the different program transmitting sets Pt, P and P the drawing, which is purely diagrammatic shows the contacts arranged in a straight line they are in practice arranged in a circle concentric with the switch shaft so as to permit the switch arms to sweep across them in the rotation of the shaft. While only three vertical rows of contacts are here shown it is to be understood that they may be more or less in number and that in any case the first few vertical rows of contacts are left blank or disconnected, for example, in the present case the first five, leaving the sixth vertical row of contacts the first ones that are connected with the operating cirthe lower contacts of the sixth, seventh andeighth pairs being connected respectively to the bus Wires of filament batteries F, F", and F 8 respectively. In the horizontal row of contacts 33 the upper members of each pair areconnected in multiple to the conductor 49 which supplies battery current for the test by its, connection through repeat relay 50, conductor '46 and bus 48 to the central office common battery B. The lower contact members of the horizontal row 33 are connected individually to the upper bus wires of the different filament batteries F, F, and F Thus the batteries B, B and B, the program transmitters P, P, and P and the filament batteries F, F, and F are associated individually with the sixth, .sev-

,enth and eighth vertical rows of contacts,

cuits so that the switch must make five steps before effecting any circuit connections, after which the Wipers will bev movedsuccessively to the sixth,seventh' and ei hth vertical rows. The purpose of provi ing this lost motion or blank steps will be made clear in the descriptionof operation. The

switch wipers 2324 connect with the adja-.

cent terminals of the winding. 34 35 of a repeating coil 36, the remote terminals of ment of the tube 37, while t e wipers 26 which windings connect to the plate and filament of the audion tube 37. The switch wipers 2526 connect to the rid andfil'aand 28 form the terminus of the filament of the tube 37. The wiper 27 is connected to the multiple test wire 3, leading into. Fig. 1. The horizontal row of contacts 30 are'co'nnected as multiple pairs, the upper and lower members beingconnected respectively to the remote terminals of the coils 38 and 39 of'the repeating co il 36 through the con respectively. The stepping ma net 11 and .release magnet 15 have their windings connected in multiple, one side to ground and the other side through conductor 51 to an impulse wire 40 leading into Fig. 1 where it terminates in a front or normally open con- ,tact 52 of the line relay L, which contact is engaged by the armature 53 connected through wire 54 to the exchange common battery B. The conductor 51 is also connected in'multiple to a normally open contact 55 engaged by the armature 56 of the relay 50, the armature 56 being connected by way of conductors 46 and 48 to the exchange common batteryB. The repeat relay 50 is controlled ,by the sleeve relay 42 through the armature 57 which is arran ed, as shown, to close a shunt around the winding of the relay-50 by way of resistance 58, armature 57 and conductor 59. The subscribers broadcast receiving set A is-similar in all re- .receiver.

mittin devices P P and P are referably radio receivers of a type adapted to receive radio broadcast matter from near or distant points and amplify and relay the the second stage of amplification is effected through an audion tube 37 individual to each line.

In the operation of the arrangement shown in Figs. 1 and 2, the subscriber at station A operatively connects his broadcast receiving or extension set A to'the line by inserting the receiver plug P in' the jack J 2 which connects his receiver 64 across the line multiples 5 and 6 through the booster coil windings 6065 and condenser 66 in series, and closes a path for direct current between the multiples 5 and 6 through coil 60, lower spring of jack J transmitter 62, and automatic dial 63. This energizes the 'subscrib ers line relay at the central oflice in the usual manner by current from the central office common battery B, which energizing circuit may be traced from the grounded side of central oflicecommon battery B,:conduc tor 68,- right hand winding of line relay L, line conductor 69, to subscribers substation A, line multiple 5, to subscribers broadcast receiving sets A (Fig. 2), coil 60, transmit-' ter 62, contacts of dial 63, conductor 6, 70, left hand winding of line relay L and back to the battery B. Energization of the line relay energizes the line lamp L by closure of a local circuit which may be ,traced from the battery B through elements 54:, L 71, 68 and back to battery B. This causes the line lamp L at the telephone operators switchboard to glow, but only for a moment as the subscriber wanting broadcast service will immediately operate his dial to break and make his line circuit a certain number of times according to the particular program he desires which breaks and makes will cause his line lamp to flicker instead of glowing steadily an-dso indicate to the telephone operator that the subscriber is notcalling for a telephone connection but is automatically setting up his connection for broadcast reception. As the dial 63 is of the well known type used in automatic telephony and well understood in the art, it will not be necessary to describe the samehere in detail and it suffices to say that it operates automatically to effect one or a series of breaks of brief duration inthe line circuit according to the setting of the dial each time it is set and released. The first closure ofthe line and enei'gization of the line relay L completes 'an energizing circuit for the stepping magnet 11 (Fig. 2) which may be traced from the free side of the common battery B througlf circuit eleinents 54', 53, 52, 4, (into Fig. 2),

'51 to stepping magnet 11 and release magnet 15 in multiple and thence through ground back to the grounded side of battery B. It is to be noted here that the release magnet 15 is made sluggish in its action so that it will not respond to the energizing current until after a lapse of time much longer than the interval bet-ween the breaks and makes of the subscribers dial 63 so that when the subscriber first closes his circuit,

as just described, the stepping magnet 11 will first operate to step the switch 9 around one step releasing the detent 19 after which, the time period of the release magnet 15 having lapsed, this magnet will actuate its armature to move the hook 21 up into engagement with the detent 19 and the extension 16 into engagement with the dog 14 which disengages the dog from the ratchet 13 and also throws the pawl 12 out of engagement with the ratchet, thus causing the switch to release and return to normal posi- 'the line relay L to retract its armature 53 and open the circuit of the stepping and release magnets 11 and 15. To prevent the subscribers broadcast selector switch 9 from being stepped around and connecting broadcast matter on to his line due to one or more accidental breaks in his line circuit while the subscriber is waiting for telephoneoperator service, the selector switch 9 is provided with several blank contactspreceding those rep-- resenting the difi'erent broadcast programs In the present illustration the first five contacts are left blank, the series of active 'contacts beginni with those of the sixth verticalrow, as indicated in Fig. 2, where the blank contacts are not shown, it being understood that the switch must make five steps before its wipers engage the firstset of active cont cts. Thus if the subscriber, while wa ting or an operator should accidentally, mo-

mentarily open hisline or impatiently oplector switch around to the fift broadcast program, the subscriber, shortly after the initial closure of his line effected by his insertion of the plug P in the jack J and before the line lamp has been energi'zed sufiiciently long to indicate a telephone call to the operator, sets his dial to a number corresponding to the number of the broadcast program he wishes to receive, which in the present case would be some number above five, and permits the same to release producing a number of breaks corresponding to the settin of the dial. Assuming the setting to be eig t, the dial upon release will cause the line circuit to be momentarily opened eight times. The first five breaks in the line circuit will cause the armature 53 of the line relay to open and close its connection with the contact 52 five times, thus stepping the secontact, the 7 period of closure of the contacts 5253 bea ing sufiiciently brief to prevent actuation of the release magnet 15. Upon the sixth mo-' mentary' break and subsequent make of the line circuit, the switch 9 will step on to the sixth or first vertical row of'active contacts whereupon the line cut-off relay L will be energized and the control of the stepping magnet 11 transferred from the line relay to the ring side relay 420i the switch circuit. The energizing circuit of the cut-off relay L may be traced from the common battery B (top of Fig. 2), bus wire 48, conductor 46, winding of repeat relay 50, conductor 49, upper member of the sixth contact of hori-- zontal row 33, switch wiper 37 conductor 3, into Fig. 1 line cut-oft relay= L conductor 69 to grounded side of the common battery B. Energization of repeat relay 50 causes 1 its armature 56 to engage thecontact 55 thus maintaining the stepping magnet 11 energized by current from battery B through circuit elements 48, '46, 56, 55, 51, 11 to ground 'and back to battery B, while "the energization of the cut-off relay L (Fig. 1) disconnects the line relay L in the; usual manner-which becoming deenei'gized releases its armatures 71-53, extinguis ing the line lamp and opening the circuitthrough conductor 4." Simultaneously with the energization of the cut-off relay L and repeating relay 50, the sleeve relay 42 is energized by current from the common battery B through the circuit elements-48,46, 39,. 42, 41, lower member of the sixth contact in the horizontal row 30, switch wiper 8, line multiple 2 into Fig. 1, line wire70, multiple wire 6, into Fig. 1, through circuit elements 63, 62, 60, 5 into Fig. 2, 69, 1, into Fig. 2, 7, 40, 38, 45, 47, and back to the grounded side of the common battery B. Energization of ring -side relay 42causes its armature 57 to be attracted and complete a shunt around the winding of repeat relay 50 by way of c1rcuit switch wipers 2526 and the eighth air of filament rheostat 80, 28, 81, 82, back to battery F ,As the winding 60' of the booster return to normal ready for the next' step.

The next or seventh'mom'entary break in the subscribers line circuit, which follows immediately, effects a momentary release of the armature 57 of sleeve relay 42 which causes a momentary energization of the repeat relay 50 which in turn effects. a momentary closure of the contacts 5650 and a momentary energization of the stepping magnet 11 to step the switch wipers around to the seventh vertical row of contacts. The energizing circuit of the stepping magnet-may be traced .from the common battery B through circuit elements 48, 46, 56, 55, 51, and 11 back to'the grounded side fof battery B. Similarly, the next or eighth momentary break in the line causes the stepping magnet 11 to be again momentarily energized and step the switch wipers around into engagement with the eighth vertical row of contacts.

After the eighth momentary break in the line circuit the subscribers .dial 63 comesto rest and maintains the line circuit closed.

The line now being closed, the ring side relay 42 is maintained energized which maintains the repeating relay 5O deenergized by 9 virtue of the closure of the shunt around its wmding which in turn maintains the circuit of the stepping and release magnets 11 and 15 open at the contacts 55--56. The switch wipers thus come to rest on the eighth ver-'" tical row of contacts, maintaining the input terminals of the subscribers. line tube 37 in 0 erativefconnection with the bus wires 68 o the program transmitter P through contacts in the horizontal row 32. urrent is' supplied to the output-or plate circuit, of

the tube 37 from battery B individual to the program transmitter P over circuit elements 72, 73, 23, 74, 34, plate of tube 37, filament of tube 37, '75, 35, 76, 24, 77, 78, back to battery B. As the coil 36 is arepeating coil of the well known type having the four windings 34, 35, 38, 39 on a common magnetic core the output or plate cirscribers line through the coils 38-39 which are included in series in the subscribers line circuit as hereinbefore traced. Thefilament circuit of the subscribers audion tube 37 dividual to the program transmitter P, over the circuit elements 79, lower member of bus wire 68, 26, filament of audion tube 37,

coil 61 at the subscribers broadcast receiving set A is included in series, in the line the W broadcast matter coming thereover is repeated in the winding 65 which reproduces 13 0 1 15 cuit of the tube 37 is coupled to the sub- 1'20 may be traced from filament battery F, in- I the signal in the subscribers receiver 64 over a circuit which may be traced from 65 through circuit elements 66, 63, 62, and through the receiver 64 back to winding 65 byway of the plug and jack connection I P --J As the battery supply relay 42 is held energized during the subscribers use of his line forreceiving broadcast, should a reception of broadcast so that if the call is an emergency one the operator may lug in regardless of the busy condition. hus a special tone test iseifected by the usual tone test apparatus indicated in Fig. 2 as consisting" of the inductance 87 connected in series with a circuit breaker 88 and inductively related to the coil 58 in series in the test circuit. The energizing circuit of the coil 87 may be traced from the common battery B through the circuit elements 48, 46,

87, 88, back through ground to the batt y B When the subscriber wishes to discontinue the broadcast reception he withdraws the plug P which opens the line circuit at the jack contact 89. This deprives the sleeve relay' 42 of current whereupon its armature 57 is retracted removin' the shunt from the repeating relay 50 whidl i thereupon becomes energized and closes the circuit of both the stepping magnet and the relay magnet through connection of the armature 56 with contact 55. This circuit may be traced from battery B through the circuit elements 48, 46, 56, 55, 51, 11 and 15 in multiple to ground.

' and back to the battery B. After the brief lapse of time required for the operation of the release magnet 15 this magnet attract-sits armature which brings the extension 16 into engagement with the dog 14 to trip the same which in'turn trips the pawl 12 allowing the switch to return to normal, hook 21 engaging the detent 19 which holds the armature 17 in' its actuated position during the restoring movement of the switch and until the switch' reaches the normal 'position' whereupon the cam 22 operates to disengage the detent 19 from the hook 21 and permit all parts of the switch to return to the normal position shown. When the switch in restoring moves its wipers off the sixth vertical rowof contacts the circuit repeat relay 50 is brok'enat the wiper27, and the repeat relay 50 deenergizing opens the circuit of the magnets 11, and 15 at the contact 55-56. This puts all the circuits and apparatus in the. normal condition shown in Figs. 1 and 2.

For, metering the subscribers use of the radio broadcast service on a basis of time use, a meter controlling actuator 90 (Fig. 2 is arranged to control the subscribers telephone meter M (Fig. 1) through the opera-; tive connection of the switch circuits .ogt' Fig. 2 with the subscribers central office line" be traced from the meter generator 91 (Fig. 2) .through commutator 90, switch 92, bus wire 93, switch 94, wire 49, the upper member of one of the contacts in the horizontal row 33, wiper 27, test-wire 3, into Fig. 1, wire 95, high voltage winding 96, of the meter M, to ground and back to the grounded side of the meter generator 91 (Fig. 2). When the meter armature 97 is retracted a suflicient distance to close the contact 98 the low voltage winding 99 of the meter M is closed thus aiding in the further attraction of the armature and the actuation of the meter as well understood in the art, which actuation will be repeated terminal circuits. This control circuit may,

at intervals according to the intervals of the closing and openinTgl of the circuit meter commutator 90. ese periodic 'registrations of the meter during use of the broadcast apparatus will of course be added to those produced by the actuation of the usual, telephone 0 erators metering key 100, so that the subscribers use of the broadcast service is charged'in the same units as that of the telephone use and the amount of service represented by the unit charge varied according to the speed-0f operation of the commutator 90.. Where the service to some of the lines is to be given free the switch 94 individual to the line is opened and where the service is to be given free to all or a group of lines the switch 92 is opened to disconnect the commutator from the bus 93 common to all or a group as the case may be.

Referring now to Fig. 3, this is similar to Fig. 2, just described, except that the line multiples 1--2 are permanently connected to the outside terminals of the coils 38 and 39 and the-battery connection to the inside terminals of these coils controlled through the upper pair. of wipers 7-8 of the switch 9, and the horizontal row 30 of the switch bank contacts. Another difference is that the repeat relay is omitted and the stepping of the switch, after connection with the active contacts, controlled through a back or I normally closed contact of the ring side revlay 42 connected to battery through an off normal switch 101 controlled by a cam 102 on the switch shaft 10 arranged to maintain the 011 normal switch closed only during engagement of the switch wipers with one of the sets of active contacts that is, from the sixth vertical row on. As this is a modification of the switching circuit illustrated in Fig. 2 and intended to operate in place thereof, it is to be read in connection with Fig. 1. The conductors 1, 2, 3, 4, 5 and 6 of Fig. 3 tie on to the similarly numbered v conductors of Fig. 1. In the operation of this circuit-arrangement when the subscriber operates the dial 63 at his broadcast receiving set A ,to effect the eighth successive momentary breaks in his line circuit, the first six cause the line relay to close the contact 52-53 six times which in turn effects six successive energizations and deenergizations of the stepping magnet 11, the successive impulses being as before described, of too brief duration to cause actuation of the re- .lease magnet 15. The energizing circuit of stepping magnet 11 may be traced from battery .B (Fig. 1) through circuit elements 53, 52, 4, into Fig. 3, 51, 11, and through ground back to battery B. This causes the switch 9 to step around to the sixth vertical row of bank contacts whereupon the cut-off relay L (Fig. '1) is energized by current from battery B (Fig. 3) through the circuit elements 58, upper contactsof row 33 of the switch bank contacts, 27, 3,"L 68, to ground and back to battery B. At the same time battery is supplied to the subscribers line in series with the ring side relay 42 over a path which may be traced from battery B (upper part of Fig. 3) through upper members of row ofthe switch bank contacts, circuit elements 7, 140, 39, 42, 2, 70, to subscribers station and back by way of 69, 1, 38, 141, 8, lower contacts of row 30, .back to battery B. The seventh break in the line,

' effected by the subscribers dial 63, effects a momentary deenergization of the sleeve relay 42 whose armature falling back produces a momentary closure of the circuitof the stepping magnet 11 whose energizing circuit may mow be traced from battery B (Fig. 3), through wiper 7 to wire 140, as before traced, and thence through off normal switch 101, the cam 102 now having moved into a position to close the same, thence through circuit elements 103, 104, 105, 51, 11,

and through, ground back to battery B. Similarly upon the eighth break in the line circuit, the switch 9 is stepped again, this time onto the eighth vertical row of contacts,--whi'ch connects the input circuit of the I -subscribers -line tube 37 onto theprogrambus wires 68through the eighth pair of con-e tacts in row 32 and switch wipers,25--26.

The switch wipers 2324 engaging the eighth pair of contacts, connectthe battery B individual to the Number 8- pro am, through conductors 74 and 76 throng the windings 34 and 35 of the repeat coil 36.

- scribers line tube 37 ,while the switch. wipers row 33 and'so supply current over thesuhto the" output or plate circuit of'thesub- 7 and 8 maintain the connection with the battery B through the multiple contacts-of scribers line as before traced. Also,-'as"in Fig. 2, the filament circuit of the subscribers line -tub,e, 37 will be supplied with current from the filament battery A i 11dividual to the Number; 8 program, the connections for this being the same as that of Fig. 2. Also, as in Fig. 2, the cut off relay, busy test and meter control circuit 3' is completed through wiper contact 27. The circuit of the cut off relay may be traced from battery B (Fig.

3) through the circuit elements 58, upper member of the engaged contact in row 33, 27, 3, into Fig. 1, L 68, and back to battery B. The tone test is imposed upon .this circuit by thecoupling of the tone test coil 87 with the coil 58 included; in the test circuit in the usual manner well understood in the art, While the meter actuating source 91 and commutator are connected withthis circuit.

the number of switch wipersare' reduced to a minimum by delegating the control of certain circuits which are common to all the programs, to a cam actuated switch operableto maintain said circuits closed only during the engagement of the switch wipers with the program contacts. In this, as in the other switch arrangements previously described, the contact bank of the switch is provided with several vertical rows of blank contacts, for example five in number,- notshown, for the purpose of permitting the switch to be stepped around several steps without effecting connection with any program transmitters. Parts of the present switchin arrangement which are similar to and perform the same function as corresponding parts inthe previously described switching arrangement, are simllarly numbered. For example, the battery supply for the output circuit of the s'ubscribers line tubeor relay 37 isfurnished through wipers 23 and 24 and the top rowof bank con tacts, the connection between the input cir-.

cuit of the subs'cribers line relay tube 37 and the program source is effected through wipers 25 and 26 and the second horizontal row of bank contacts, the filament current supply is furnished through wipers26 and 2 9 and their associated contacts, and the metering circuit is connected through wiper 27 and its associated contact, with the meter actuating source. All of these. circuits are of the switch. Thus, circuit congram 1 such as the connections effected through' the multiple line conductors 1'-2, test conductor 3, and impulse conductor 4,

to be cOnnected withsources individualto .a program and s0 theircontrolis delegated to -t he wipers which change connection with each step 'neetions which are not individual to a proare controlled through the cam operatedswitch 145. a This switch is controlled by the cam 146 carried by the switch shaft 10 to maintain the contacts open when the switch is in its normal position or has moved into a position in which its wipers are on any of the blank contacts, and will maintain its contacts closed in any position of the switch in which the switch wipers are in engage- .ment with a set of the program contacts. Another feature characteristic to the present switch arrangement is the position of the individual meter IM individual to the switch circuit so as to meter only the use ofothe subscribers line for broadcast 'reception As with the other switching diagram, the present diagram is to be read in connection with Fig. 1, the conductors 1, 2, 3, and '4' of Fig. 4 tying onto the conductors-1, 2, 3 and- 4 of Fig. 1 respectively.

In the operation of this arrangement, the

impulses sent over wire 4 from the subscribers line relay,in Fig. 1, pass directly to the stepping magnet 11, through conductor 146 until the switch has been stepped around to the sixth row of contacts whereupon the contacts of switch 145 are closed, the sleeve relay.42 ,energized in series with the subscribers line and the cut off relay in Fig. 1 energized to disconnect the line relay, which now causes the 'further stepping oh the switch to be controlled through the sleeve relay as a repeating relay responding to breaks in the subscribers line circuit. The (Fig. 1) may be lamp 147, conductor 148, contact of switch 145, conductor 3, into Fig. 1, cut off relay L conductor 68 to ground and back 'to battery B. The energization of the cut off relay. L causes the line relay L to become deenergized and open the circuit through the impulse conductor 4 as before described in connection with Figs. 1 and 2. At the same time the cut ofi' relay is deenergized to bring about the disconnection of the circuit through conductor 4, the ring side relay 42 is energized in series with the subscribers line by acircuit which may be traced from battery B through the circuit elements 39, 42, 2,70, over thesubscribers line and back by way of circuit elements 69, 1, 38, to battery B.- Upon the next momentar break .in the subscribers line circuit the r1ng side relay 42, being energized in series therewith,

is momentarily deprived of current which causes a momentary retraction of its armature, which in turn closes the circuit of the stepping magnet ,11' which may be now traced from battery B through the circuit elements 104, 105, 146, 11; to ground and back to battery B; Thus, each momentary break in the subscribers line circuit causes the switch to make one step. 'When the switch comes to rest with its switch wipers ance 149 thus extinguishing the signal light.

' This is the operating. position of the switch,

and during the maintenance of this con-' nection, assuming the switch wipers to be in contact with the vertical row of bank contacts associated with the number 7 program, the individual, broadcast service meter will be intermittently energized in a circuit which may be traced from the meter energizing source 91, through commutator 151, switch 152, upper member of the bottom pair of contacts in the eighth row, switch wiper 27, conductor 153, meter IM to ground and back to the source 91. It will be noted here that-by movement of the switch arm 152 to its right hand contact the meter will be controlled through the commutator 151 instead of 152. As these commutators are arranged to close and open the circuit at different periodicity, the meter will beoperated' at a different rate thus making a different charge per hour for the service. For the purpose of assigning different rates to difl'erent programs the switches 152 and 154 included in the meter circuits of the different programs, respectively, are arranged, as shown, with diflerent contacts connected with the diifercut commutators 150 and 151, respectively.

Thus, with the meter control commutators 150 and 151 associated with different programs, the subscribers service charges as recorded by his broadcast meter IM will vary according to the particular program taken by him. To enable the operator or supervisor having charge of a number of switching de-- vices like the present one, to listen in on the subscribers line in the usual manner as in a telephone operators cord circuit for the purpose of communicating with the subscriber, a listening key K is provided arranged to connecta suitable listening set, 11 not shown. The subscriber may apprise such supervisor of his wish for some special service by making several successive momentary breaks in his line circuit much in excess of that required for the stepping of the switch to any of the sets of program con tracts 'duringawhich the su ervisor noticing the apparent constant fllckering of the supervisory lamp-147, will operate the, listening key'K to ascertain the wants of the subscriber. To enable the supervisor to call the subscriberduring the connection of his line through the switch mechanism, a special signaling key S is provided WhlCll is ar-a ranged to connect theinductance coil 154, across the subscribers line, which coil is inductively connected" with the special tone signal circuit and thus puts the signal on. the line to be heard in the subscribers loud speaker. {To enable the subscriber to receive other broadcast items not on the programs to which his switch has access, the last vertical row of contacts in the switch have their program contacts such as 155 connected to a special program trunk 1.56 terminating in a jack 157 situated before what may. be termed a special program operator who has access to trunks leading to other stations providing different broadcast items, and who is also provided with means, such as telephone plugs forming the terminals of such trunks, for connection of any of said trunks to the special program contacts 155 through the jack 157, and short trunk 156. When the subscriber desires such special items he signals the supervisor in charge of the broadcast service by sending in the excessive number of breaks to signal the supervisor through actuation of the lamp 147 as before described the extra number of breaks in the line circuit causing the switch to step around to'the last vertical row of contacts and there, come to rest, which disconnects the subscribers line from all of the regularprograms' and connects 1t through the swltch wipers 25-26 and special programs contacts 155 to the trunk 156 terminating in the jack 157. The supervisor listening in through use of the key K may now ascertain the wants of the subscriber and communicate the same to the special program operator over a suitable order circuit not'shoyvn. The special program operator may then give the subscriber the program or item desired, by inserting the terminal plug of the appropriate trunk in the jack 157. 'This trunking ar-v rangement for supplying the special programs from other stations will ,be clearly understood from an inspection of Figs. 5 and 6.

In Fig. 5 is diagra-mmeda portion of a general system of broadcast distribution comprising amaster station A, district stations B, subscribers central stations C, and

subscribers substations D, the relation of the stations A, B andC being the same as thatdescribed in my copending application Serial No. 746,357, filed October 28, .1924. It sufiices here to say that the station A- is a master station for the system having means for ori inating or relaying broadcast matter to t e B stations, either by radio or over t'runkvlines, such as 158 and 159, that the B stations have means fororiginating or relaying broadcast matter from the A station or stations outside the system -to C stations,

and that the C station s, together with the subscribers substations Dare provided with 'means'in the form of the circuits herein previously described in detail, for originating or relaying broadcast matter from the B stations to the subscribers stations 1). The

broadcast matter is originated or received q 0 159 and 158 are s mbollcal of a from the other stations and put onto the program contacts of the subscribers selector switches by any known or other suitable form of apparatus symbolized at P, P, and

P in Figs. 2, 3 ando4.

In Fig. 6 is shown diagrammatically, the special trunking system enabling a subscriber at a D station to extend his line beyond his associated central station either directly, or through other stations of the system to some particular station for the purpose of receiving the broadcast program there originated or there available through suitable whose input circuit terminates in a jack 162. i

Similarly, the station B is provided with the circuit LB arranged to connect the jack 162 with the iack 163to an amplifier unit IA, the jack 163 forming the terminal of a trunk 159 which terminates in the output. circuit of a line tube 237 at the A station, the input circuit of which tube terminates in the jack 164. At' the A station is provided an amplifying link circuit LA the same as that. ,of station B arranged to connect the jack 164 with a jack 165 forming the terminal of a trunk 158 terminating in a line tube 337, and jack 159 at station B in the same manner as that of the trunks 159 and 161. At the station B is provided a link circuit LB similar to those at stations A and B and arranged to connect the jack 159 with the broadcast program apparatus 166 which may be a local. source ilof broadcast matter or suitable relay device-capable of relaying broadcastfromf some other station. Thus, with the trunking system so described the subscriber at a D station'may extend his line to the broadcast transmitter 160 of the station B over the trunking connection which may be traced from 160 through the trunking elements LB 159, 337,158, 165, LA, 164, 237, 159, 163, LB, 162, 137, 161,160, LO, 157,37 to subscribers station D. In the present illustration this broadcast matter is transmitted from the station B over the triinks 158, 159, and 161, by carrier current, which is detected and amplified in the detector amplifier unit DA at the C station and from thence transmitted to the subscribers station at audio frequency or in the form of the original modulations, the amplifier units IA- at the stations B A, and B being operable on the intermediate or carrier current fref istribution 1 0 out from any of the stations to several C stations directly or through other stations. It is also to be noted that the outgoing terminal of each trunk line is provided with a line tube similar to that of the subscribers line tube which acts as an amplifier or relay so that throughout the several links, the line tubes or relays will operate to cfi'ect gradual amplification throughout the distribuion thus avoiding the losses and the necessity for currents of large magnitude incident to long distant distribution without the use of increments of power between the source and destination; It will be obvious that where conditions are favorable, the amplifiers IA at the intermediate stations A, B, etc. may consist of but one step or may even be omitted or replaced by suitable coupling means,

the line tubes or relays 137, 237, etc., being relied upon or eiiecting the necessary amplification. 1

The arrangement of circuits and apparatus for carrying out the idea of distribution with gradual amplification or increments of power at a broadcast distributing central is diagrammatically shown in Fig. 7, where a source of audio signals is indicated at 167, the signals of which are distributed through a transformer 168 and a group of several amplifier tubes 169 in multiple to theinput side of a suitable cou ling means such as the audio transformer 1 O, the output side 0 which distributes throughseveral amplifier tubes 37 to as many trunks or line circuits 173. The line circuits 173 represent the subscribers lines such as 'the subscribers line- 69-70 of Fig. 1, while the amplifier tubes 37 represent the individual line tubes or relays such as 37 of Figs. 2, 3, etc. It will thus be seen that with this arra'ngementthe containing claims to the service metering and differential metering which are dis closed but not claimed herein.

What I claim is:

1. In a system of radio broadcast distribution, a central station, subscribers stations and wire lines interconnecting them, meansat the central station to receive, broadcast modulated waves, and relaymeansalso at. the central station, individual to the lines, for connecting with said broadcast receiving means in common and adapted to relay the modulations received from said broadcast connection, to the subscribers over their wire lines individually.

2. The system claimed in claim 1, with means at the subscribers stations for individually controlling the line relaying means,

over the wire lines.

3. The system claimed in claim 1, with'the line relaying means consisting of individual vacuum tubes, or valves, one for each line,

at the central station, and means whereby I the input sides of said line tubes may be connected in common to receive the output of the central office transmitting or relay apparatus, and the output side of each line tube may be simultaneously and separately connected. to its own line.

4. The system claimed in claim 1, with the line relaying means consisting of individual vacuum tubes, or valves, one. for each line, at the central station, and means whereby the input sides of said-line tubes may be connected in common to" receive the output of the central oflice transmitting or relay. apparatus, and the output ,side of each line tube may be simultaneously and separately connected to its own line, together with means at each subscribers station to control the connection of his ownline tube atcentral.

. 5. The system claimed in claim 1, with the line relaying means cbnsisting of individual vacuum tubes, or valves, one for each line, at the central station, and means whereby the input sides of said line tubes may-be connected in common to receive the output of the central ofiice transmitting or relay appa ratus, and the output side of each line tube may be simultaneously and separately con nected to its own line,together with means at each subscribers station to control the connection of his own line tube at central, and to disconnect the same when not receivmg.

6. In a system of broadcast distribution, a central station and subscribers stations, .and

wired line'circuits interconnecting them, a.

transmitter'at the central station adapted to send out broadcast matter and a'plurality of vacuum tubes or valves, one for each sub scribers line at the central station, having their input or grid terminals adapted for connection to said transmitter in common and their output or plate terminals separately connected to their respective lines individually.

7. In a system of broadcast distribution, a central station and subscribers stations, and wired line circuits interconnecting them, a transmitter at the central station adapted to send outbroadcast matter and a pluralit' of vacuum tubes or valves, one for eac subscribers lineat the central station, having their input or grid terminals adapted for connection to said transmitter in comwired line circuits interconnecting them, a

men and their output or plate termfiials red for connection to said transmitter in comseparately connected to their respective lines mon and their output or plate terminals sepindividually, together with sources of curarately connected to their respective lines rent supply at the central station for all said tubes.

individually, together with automatic switching means controlled by the subscribers over 8. In a system of broadcast distribution, a their line circuits for connecting and disconcentral station and subscribers stations, and necting their line tubes.

transmitter at the central station adapted to a central station and subscribers stations, send: out broadcast matter and a plurality and'wired line circuits interconnecting them, of vacuum tubes or valves, one for each a transmitter at the central station adapted subscribers line at the central station, havto send out broadcast matter and a plurality ing their input or grid terminals adapted of vacuum tubes or valves, one for each subfor connection to said transmitter in comscribers line at the central station, having men and their output or plate terminals septheir input or grid terminals adapted for arately connected to their' respective lines Connection to said transmitter in common individually. together with switching means and their output or plate terminals separat the central station for connecting said line ately connected to their respective lines intubes to said transmitter, and means at subflividually, together with automatic switchscribers stations for controlling said switchmg means controlled by the subscribers over ing means over their wire lines. their line circuits for connecting and dis- 9. In a system of broadcast distribution, connecting their line tubes to and from the a central station and subscribers stations, l Office transmitter. and wired line circuits interconnecting them, In a system of broadcast distribution, a transmitter at the central station adapted a Central Station n Subscribers stations, to send out broadcast matter and Ya pluraland wired line circuits interconnecting them, ity of acuum tubes or val eg, one for each a transmitter at the central station adapted subscribers line at the central station, havto send out broadcast matter and a pluraling their input or grid terminals adapted ity of vacuum tubes or valves, one for each for connection to said transmitter in com subscribers line at the central station, havmon and their output or plate terminals scping their input or. grid terminals adapted .aratelyconnected to their respective lines inf r connec ion to said transmitter in common dividually, together with switching means and their output or plate terminals saparateat the central station for connecting said line 1y connected to, their respective lines individtubes to said transmitter, and means at subly, together with automatic SWitChiIlg scribers stations forcontrolling said switchmeans controlled by the subscribers over ing means over their wire lines to connect their line circuits for connecting and disthe tubes for receiving and to disconnect the connecting their line tubes to and from the same at will. v

10. In aisyste-m of broadcast distribution,

.a central station and subscribers stations.

central office transmitter on one side and to and from their lines on the other.

14. In alsystem of broadcast distribution,

v and wired line circuits interconnecting having a central station and a plurality of them, a transmitter at the central station subscribers stations, a primary source of adapted to send out broadcast matter and a broadcast electrical waves, and means at the plurality of vacuum tubes or valves, one central station to relaythe same in stages for each subscribers line at the central staincreasing in both volume amplification and tion, havingtheir input or grid terminals in number of units of amplification, the last adapted for" connection to said transmitter in setof units being equal in number to the common and their output or plate terminals subscribers stations together with means to separately connected to their respective lines bring into service units of-the last or line set individually, together with sources 'of cur-' in response to the call subscribers for broad- 12. In a system of broadcast distribution,

rent supply at the central station for all cast service, whereby the final or line stage said tubes, and means controlled by the sub- 0f amplifi at n 1 x y P P scribers over their wired line circuits to ate to the number of'lmes taking'such servconnect said current" sources to the tubes for ice. V energizing the same. p 15. In a system of broadcast distribution, 11. In a system'of broadcast distribution, having a central station and a plurality of a central station and subscribers stations, subscribers stations, a primary source of and wired line circuits interconnecting them, broadcast electrical waves,and means at the a transmitter at the central station adapted central-station to 'relaythe same in stages in,-

to send out broadcast matter and a plucreasing in both volume amplification and'in rality of vacuum tubes or valves, one for number of units of amplification, the last set each spbscribersrline-at the central station, of units belng equal in number to the subhaving their input or grid terminals adapt-v scribers stations, and individually appropriuted to their use, one to each, together with means to bring into service units of the last 'with switching means to interconnect each subscribers relay unit interchangeably with the central. station transmitters.

17. In a system of broadcast distribution, a central station and .subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at the central station, and individual broadcast repeating relay units also at the central station, one for each subscribers line circuit," with switching means to interconnect each subscribers relay unit interchangeably with the central station transmitters, said switch ing means being selectively controlled by the subscribers.

18. In a system ofbroadca-st distribution, a central'station and subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at the central station, and individual broadcast repeating relay units also at the central station, one for each subscribers line'circuit, with switching means to interconnect each subscribers relay unit interchangeably with the central station transmitters, and controlling means at the subscribers stations for said switching means.

19. In 'a'sys'tem of broadcast distribution, a central station and subscribers stations and wired line circuits interconnecting them, a plurality of'broadcasting transmitters at the central station, and individual broadcast repeating relay units also at the central station, one for each subscribers line circuit, with switching meansyto intercon- .nect each 'subscribers relay unit interchangeably with the central station trans-- mitters, said switching means being'located at the central station, and controlling means at the subscribers stations for said switching means.

20. In a system of broadcast distribution, a central station and subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at the central station, an d 'individual broadcast repeating relay units also at the central station, one for each subscribers line circuit, with switching means to interconnect each subscribe'rs relay unit interchangeably with the central station transmitters, said switching means being individual to the subscribers relay units and lines, and controlling means therefor at the subscribers stations, acting through' the wired line circuits.

21. In asystem of broadcast distribution, a central station and subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at the central station, and individual broadcast repeating relay units also at the central station, one for each subscribers line circuit, with switching means to interconnect each subscribers relay unit interchangeably with the central station transmitters, said switching means comprising a selector switch individual to each line, containing terminals of the'output circuits of the central otiicc transmitters. I

22. In a system of broadcast distribution,- a central station and subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at thecentral station, and individual broadcast repeating relay units also at the central station, one for each subscribers line circuit,-

with switching means to interconnect each subscribers relay unit interchangeably with the central station transmitters, said switching means comprising a selector switch individual to each line, containing terminals of the output circuits of the central office transmitters, and other terminalsv adapted to connect'the line tube to the line circuit.

23. In a system of broadcast distribution, a central station and subscribers stations and wired line circuits interconnecting them, a plurality of broadcasting transmitters at the central station, and individual vacuum tube relay units also at the central station, one for each subscribers line circuit, with switching means to interconnect each.sub-

scribers relay unit interchangeably withthe central station transmitters, said switching means comprising a selector switch individual to each line, containing terminals of the output circnits of the central office transmitters, and other terminals adapted to connect the line tube to the line circuit and to close the energizing circuit of the tube.

24. In a system of radio broadcast distribution, a central broadcasting system and subscribers connected thereto by means of wired line circuits, centralized means for receiving modulated radio waves and for detecting the same to produce audio frequency modulations, individual audio amplifier and relay tubes one associated with each subscribers line, means for supplying current to said tubes, and means to connect the-same on their input sides to said centralized detector means, and means to separately connect each one on its output side with its associated line whereby distribution is effected over the subscribers lines, with volume amplification proportionate to the number of lines receivmg, and without interference.

' '25. ha system of radio broadcast distriv bution, a central station and, a plurality of subscribers stations with wired line circuits interconnecting them, broadcast relaying or transmitting apparatus, telephone switching apparatus at the, central station for interconnectin the lines for conversation, radio switchmg apparatus independent in its op eration, adapted to connect the lines for broadcast receiving to said relaying or trans;-

mitting apparatus, a responsive device at the central station for each subscribers line and means at each subscribers station for operating the same to effect preliminary selection as between the telephone switching apparatus and the radio switching apparatus, and

, means at a subscribersstation forcontrolling said responsive device and thereafter adapted to control said radio switching apparatus 26. In a system of radio broadcast districentral station ior each subscribers line and radio switching apparatus, becomin means at each subscribers station for operating the same to effect preliminary selection as between the telephone switching apparatus andthe radio switching apparatus, and means ata 's'ubscribers station for controlling said responsive device, together with further responsive means associated with the after said prehmm selection an adapted to respond y to. the subscribers active control for actuating said radio switching apparatus.

27. In a system oi radio broadcast distribution, a central station and a plurality of subscribers stations with wired line circuits interconnecting them, telephone switching apparatus at the central station for interconnecting the subscribers lines for conversation, broadcast,receiving and transmitting apparatus at the central station, switching apparatus also at the central station for con-' necting the subscribers lines individually with said broadcasting apparatus for receiving modulations therefrom, a signal circuit for the telephone switching apparatus, a signal circuit for said broadcast switching apparatus, a res onsive device at the central station control ed by thesubscriber to effect vpreliminary selection as between said signal clrcults; and means assoclated w1th sa1d broadcast switching apparatus adapted to be directly controlled by the subscriber and to control said broadcast signaling circuit, after said preliminary selection.

28. In a system of radio broadcast distribution, a central station'and subscribers stations and wired lin'e circuits interconnecting 1 them, telephone switching apparatus at the central station for interconnecting the lines for conversation, broadcast switching apparatus adapted to connect the lines to centralized broadcast receiving, relaying and transmitting apparatus, a signal circuit for the tele hone switching apparatus, a signal circuit or the broadcast switching. apparatus and a line relay connected with the subscribers line responsive to subscriber control normally controlling both of said signal circuits with means to disable said line relay after preliminary selection of the broadthereafter. fily responsive to the subscriber control. 3

In testimony whereof signature.

I hereunto aflir my EDWARD E; CLEMENT.

cast switching circuit and' to render the same 

